chem 106 test 4 Flashcards

1
Q

four zones of a weak acid titration and how to calculate

A
  1. initial - ICE table for the acid
  2. before equivalence point - Henderson Hasselbach
  3. at equivalence point - ICE table b/c all acid has been used up
  4. after equivalence point - all strong base (weak base is trivial) so do -log[OH-]
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2
Q

how to choose an indicator

A

changes color a little after the equivalence point

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3
Q

how to write balanced equation for solubility

A

NaCl (s) -> Na+(aq) + Cl-(aq)

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4
Q

Ksp equation

A

ex: NaCl (s) -> Na+(aq) + Cl-(aq)

Ksp = [Na+][Cl-]

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5
Q

how to solve for molar solubility

ex: AB2 -> A^2+ + 2B^-

A

Ksp = (x)(2x)^2

x will give you M

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6
Q

When is a solution saturated? supersaturated?

A

Q = Ksp -> saturated

Q > Ksp -> supersaturated (some will precipitate out)

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7
Q

ΔG equation we have to have memorized

A

ΔG = ΔH - TΔS

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8
Q

ΔS = +

A

more disorder

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9
Q

ΔS = -

A

more order

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10
Q

S is greater for (gases/liquids/solids)

A

gas > liquid > solid

disorder -> order

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11
Q

ΔG = -

A

spontaneous

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12
Q

ΔG = +

A

nonspontaneous (spontaneous in the opposite direction)

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13
Q

ΔG = 0

A

equilibrium

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14
Q

ΔH = - (exothermic) and ΔS = + (more disorder)

A

spontaneous at all temperatures

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15
Q

ΔH = + (endothermic) and ΔS = - (more order)

A

nonspontaneous at all temperatures

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16
Q

ΔH = - (exothermic) and ΔS = - (more order)

A

spontaneous at low temperatures

nonspontaneous at high temperatures

17
Q

ΔH = + (endothermic) and ΔS = + (more disorder)

A

nonspontaneous at low temperatures

spontaneous at high temperatures

18
Q

for the Nernst equation ΔG = ΔG* + RTlnQ, a small Q indicates a shift (left/right) and a large Q indicates a shift (left/right)

A

right - ΔG decreases so more spontaneous; left - ΔG increases so more nonspontaneous

19
Q

if ΔG* is negative, Keq is

20
Q

if ΔG* is positive, Keq is

21
Q

OIL RIG

A

oxidation is losing e-s (increase in oxidation number)

reduction is gaining e-s (decrease in oxidation number)

22
Q

to balance half reactions,

A
  1. balance the atoms in each half reaction first
  2. balance the electrons in each half reaction
  3. multiply the full equations by the LCM to balance the total number of electrons
23
Q

oxidation occurs at the ? and reduction occurs at the ?

A

anode; cathode

AN OX, RED CAT

24
Q

the cathode (gains/loses) mass

A

loses - ionizing

25
the anode (gains/loses) mass
gains - solidifying
26
positive voltage, electrons flow from
anode to cathode
27
an Ampere is a
Coulomb/sec
28
Faraday's constant is in units of
Coulombs/mol e-
29
E*cell =
E*red, cathode - E*red, anode
30
E*cell = +
spontaneous
31
E*cell = -
nonspontaneous
32
spontaneous reaction in terms of E*cell, ΔG*, and Keq
E*cell + ΔG* - Keq big
33
nonspontaneous reaction in terms of E*cell, ΔG*, and Keq
E*cell - ΔG* + Keq small
34
elements on the top right of the periodic table are strong ? agents
oxidizing (more electronegative means wants to be reduced more)
35
elements on the bottom left of the periodic table are strong ? agents
reducing (want to be oxidized)
36
batteries die when
they are at equilibrium; Ecell = 0 V
37
Electrolysis: if E*cell is a negative voltage,
you can put that many volts into the system to make that reaction occur
38
work: 1 J =
C * V
39
kWhr =
3.6 x 10 ^ 6 J